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Thứ Bảy, 9 tháng 3, 2013

NEW MATERIAL IMPROVING ULTRASOUND TECHNOLOGY

Ultrasound technology could soon undergo a significant
enhancement that would enable it to generate high quality, high-resolution
images, due to the development of a new key material.

The material, which converts ultrasound waves into optical
signals that can be used to produce an image, is the result of a collaborative
effort by Prof. Vladislav Yakovlev, a professor in the department of biomedical
engineering at Texas A&M University (College Station, USA; www.tamu.edu),
and researchers from King’s College London (UK;www.kcl.ac.uk), The Queen’s University Belfast (Ireland; www.qub.ac.uk),
and the University of Massachusetts Lowell (USA; www.uml.edu). Their study
findings appear in the March 1, 2013, issue of the journal Advanced Materials.

Although that technology has advanced throughout the years
similar to the improvement in sonogram images, it is still mostly constrained
by bandwidth and sensitivity limitations, he noted.These limitations, he added,
have been the chief obstacle when it comes to producing high-quality images
that can serve as powerful diagnostic tools. The metamaterial developed by
Prof.Yakovlev and his colleagues is not subject to those limitations, primarily
because it converts ultrasound waves into optical signals rather than
electrical ones. The optical processing of the signal does not limit the
bandwidth or sensitivity of the transducer (converter), which is vital for
generating very detailed images, Prof. Yakovlev said. “A high bandwidth allows you to
sample the change of distance of the acoustic waves with a high precision,”
Prof. Yakovlev noted. “This translates into an image that shows greater detail.
Greater sensitivity enables you to see deeper in tissue, suggesting we have the
potential to generate images that might have previously not been possible with
conventional ultrasound technology.”

Meaning, this new material may enable ultrasound devices to
see what they have not yet been able to see. That advancement could
significantly boost a technology that is utilized in a range of biomedical
applications. In addition to being used for visualizing fetuses during regular
and emergency care, ultrasound is used for diagnostic purposes in events of
trauma and even as a means of breaking up tissue and accelerating the effects
of drugs therapies. Whereas this research is not yet ready for incorporation
into ultrasound technology, it has effectively shown how conventional
technology can be substantially enhanced by using the newly engineering
material created by his team, Prof. Yakovlev reported.

The substance, he noted, is comprised of golden nanorods
embedded in a polymer called a polypyrrole. An optical signal is sent into this
compound where it interacts with and is changed by incoming ultrasound waves before
passing through the material. A detection device would then read the changed optical signal, analyzing
the changes in its optical characteristics to process a higher resolution
image, he clarified.

“We developed a material that would enable optical signal
processing of ultrasound,” Prof. Yakovlev concluded. “Nothing like this
material exists in nature so we engineered a material that would
provide the properties we needed. It has greater sensitivity and broader
bandwidth. We can go from 0–150 MHz without sacrificing the sensitivity. Current technology typically experiences a substantial
decline in sensitivity around 50 MHz.

This metamaterial can efficiently convert an acoustic wave
into an optical signal without restricting the bandwidth of the transducer, and
its potential biomedical applications represent the first practical
implementation of this metamaterial.”